I. Field of the Invention
This invention relates to exhaust manifolds for vehicle engines and, in particular, to an exhaust manifold assembled from two stamped halves which optimizes the flow of exhaust gases and is capable of fitting within the confined spatial limitations of modem engine assemblies.
II. Description of the Prior Art
Exhaust manifolds are utilized to direct exhaust gases from the outlet ports of the engine combustion chamber to the exhaust system for discharge into the atmosphere. The manifolds typically collect the exhaust gases from a plurality of chambers and direct the gases through a single passageway. In order to facilitate efficient operation of the engine and exhaust of the gases, the configuration of the manifold must facilitate collection and direction of the gases to the exhaust system. In early vehicles, little consideration was given to the configuration of the manifold since the engine compartment had sufficient space to incorporate the manifold. However, as the engine compartments have been reduced in size and the increased complexity of modern engines has reduced available space, vehicle designers have increasingly dictated complex and compact manifold configurations. Yet the manifold must be capable of efficiently exhausting gases from the engine.
Metal stampings were originally used to manufacture manifolds and included weld seams. However, the limitations of metal stampings limited the configurations of the manifold since manifold tubes with tight radiuses could not be manufactured. A small radius exerts stresses on the stamping which can result in failure of the manifold under the extreme operating temperatures. Nevertheless, truly compact and efficient manifolds have not been successfully manufactured in the past.
Alternative techniques for manufacturing compact exhaust manifolds have been utilized with limited success. In order to minimize weld seams which can result in stress fractures, some manifold configurations have been expanded to the desired configuration. One increasingly popular method is the hydroforming of tubular blanks. Internal fluid pressure is utilized to expand the walls of the tube to a desired cross-sectional configuration while also supporting the tube walls during bending into complex configurations. However, it has been found that the hydroformed tubes must be assembled to form the complete manifold in such a manner as to require welds in high temperature and stress areas of the manifold. The variations in temperature as the manifold is in use and then cools causes failure of these weld seams.
The present invention overcomes the disadvantages of the prior known manifolds by providing an exhaust manifold which efficiently exhausts gases from the engine and is capable of being positioned within a compact engine compartment.
The exhaust manifold of the present invention is assembled from two manifold halves stamped to include the collector chamber and the individual manifold tubes. The halves of the manifold are joined by a longitudinal weld seam which extends from the collector chamber the length of each of the tubes. A manifold flange is secured to the ends of the tubes to facilitate attachment to the engine.
The individual tubes of the manifold have a first, substantially uniform diameter over the length of the tube which expands to the diameter of the collection chamber. A plurality of exhaust tubes provide fluid communication between exhaust ports of the engine to the collection chamber. In a preferred embodiment, three exhaust tubes are incorporated into each manifold. Typically, a manifold is provided for each side of the engine. The exhaust tubes include a first tube proximate the collection chamber and directly in communication with the chamber. A second intermediate tube is in communication with a third outer tube which both direct exhaust to the collection chamber. The outer tube is most remote from the collection chamber. The individual tubes are configured to extend through specific space requirements. Additional components of the manifold may include sensors seated in the collection chamber and heat shields to protect components proximate to the manifold from extreme temperatures.
Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings.